Whether you care to call them pillow-pop or indie-disco, one thing is certain: Long Island band Twin Sister is onto something. These five twenty-somethings are like lost balloons, content to take things slow, floating between reality and their own, shimmery dream world.

The vocal performance of Andrea Estella is the key to Twin Sister’s sound. (Photos by Kyle Gustafson/FTWP)

It may not be the typical path to mainstream success, but it has earned them a dedicated following in just three years.

The group’s Monday night show at Rock & Roll Hotel drew heavily from its debut album, “In Heaven,” released in September

On stage, the five-piece ensemble — fronted by lone female vocalist Andrea Estella — meandered through bouncy basslines, psychedelic guitar solos and electro-funk keyboard sounds that felt like a nod to 1980’s synth-pop.

At the helm of it all was Estella, whose hauntingly high-pitched and husky voice whispered through each track like smoke. She inhales and exhales languorously into the microphone, letting each breath linger lazily above the band’s more warmblooded beats.

But Estella can do more than hiss and sigh. For one of the evening’s slowest numbers, “The Other Side of Your Face,” she was accompanied only by guitarist Eric Cardona, who chimed in on back-up vocals. The added space seemed to draw Estella out of her coy shell and heat up her voice to it’s rightful temperature. With refreshing authority, the two stretched open their pipes and sang mightily, a treat from a band that might be burying its best kept secret.

For now, Twin Sister’s only obstacle is its identity; too much twee can feel forced and phony. At times, Estella’s pixie-like stage presence was laid on so thick it became distracting. Swaying and posing in an billowing white sweater and tulle skirt, she placed her palm to her cheek and coquettishly twirled her hair throughout the hour-long set. Every few minutes, she blinked at the audience in a doe-eyed stare as if she’d just woken up and needed her bearings.

Watching it all can be numbing after a while, and you begin to pray for a dose of reality. Instead, you get cutesy giggles and a smattering of sleepy baby-talk.

There is an important difference between identity and affectation; one feels sincere and the other feels artificial. On the bright side, this band is young and such airs can be ironed out to make room for what truly captivates: a hypnotic, whimsical, caught-in-a-daydream sound.